Pathophysiology
Clinical meaning
Necrotizing fasciitis is a rapidly progressive, life-threatening infection of the deep fascia and subcutaneous tissue characterized by widespread fascial necrosis with relative sparing of overlying skin in early stages. Type I (polymicrobial) involves a synergistic mixture of aerobic and anaerobic organisms and typically occurs after surgery or in patients with diabetes and peripheral vascular disease. Type II (monomicrobial) is most commonly caused by Group A Streptococcus (GAS), which produces virulence factors including M protein (resists phagocytosis), streptococcal pyrogenic exotoxins (superantigens causing streptococcal toxic shock syndrome), streptolysin (destroys cell membranes), and hyaluronidase (facilitates tissue spread). The infection spreads rapidly along fascial planes at rates of up to 2-3 cm per hour, causing thrombosis of perforating blood vessels and ischemic necrosis of overlying subcutaneous tissue and skin. The nurse recognizes early warning signs (pain disproportionate to examination findings, rapidly spreading erythema, skin changes including bullae and crepitus, systemic toxicity), marks the leading edge of erythema and times observations to track spread, prepares for emergent surgical debridement (the definitive treatment), administers broad-spectrum IV antibiotics, monitors for septic shock and DIC, assists with serial...